Polymerization initiator

ABSTRACT

[2, 5, 8, 11]-tetraalkyl-[2, 5, 8, 11]-tetracyano-cis-6a&#39; carboxy, 12a&#39; oxoacide-3,4:9,10 bisdiazobicyclooctane compounds are disclosed. In one embodiment, the compounds are capable of initiating free radical polymerization and are well suited for the preparation of polymers having block type structures.

This invention relates to polymerization.

More specifically, this invention relates to a novel type of azoinitiator capable of initiating free radical polymerization.

In one of its more specific aspects, the azo initiator of thisinvention, in addition to initiating free radical polymerization, iscapable of reacting with a hydroxyl, amine or mercapto terminatedpolymer.

The use of initiators to start the polymerization of monomers is wellknown. The multifunctionality of the initiators of this invention, whichallow both free radical polymerization to occur as well as condensationtype reactions, makes the initiators of this invention particularly wellsuited for the preparation of polymers comprised of radial block typestructures.

According to this invention, there is provided a compound having theformula: ##STR1## wherein each R separately represents a methyl or ethylmoiety.

The chemical name of the above compound is[2,5,8,11]-tetraalkyl-[2,5,8,11]-tetracyano-cis-6a' carboxy, 12a'oxoazide-3,4:9,10 bisdiazo bicyclooctane.

The above compound, which is the initiator of the invention, is preparedaccording to the following reaction sequence in which each R separatelyrepresents a methyl or ethyl moiety: ##STR2##

Also, according to this invention there is provided the compoundrepresented by Structure III. The chemical name of this compound is [2,5, 8, 11]-tetralkyl-[2, 5, 8, 11]-tetracyano-cis-6a',12a'dicarboxy-3,4:9,10 bishydrazobicyclooctane.

According to this invention there is also provided the compoundrepresented by Structure IV. The chemical name of this compound is [2,5, 8, 11]-tetralkyl-[2, 5, 8, 11]-tetracyano-cis-6a',12a'dicarboxy-3,4:9,10 bisdiazobicyclooctane.

The following examples demonstrate the preparation of the compoundsidentified in Structures I through V.

EXAMPLE 1

This example demonstrates the preparation of the compound represented byStructure I.

Acetylene dicarboxylic acid (22.8 grams, 0.20 mole) and2,3-dimethyl-1,3-butadiene (32.9 grams, 0.40 mole) were dissolved in 75milliliters of a (60:40) chlorobenzene/dimethylformamide solution.

Zinc chloride (1 mole % based on the amount of the acetylenedicarboxylic acid) was added to the above solution and the reactionmixture was heated to 87° C. and held there for eight hours.

Partial precipitation of the product occurred during the Diels-Alderreaction. The reaction mixture was chilled (0°-5° C.) and about 120milliliters of hexane was added to the mixture which resulted in theprecipitation of the remaining cyclo addition product.

The Diels-Alder adduct product (identified as Structure I; R=methyl) wasrecovered as a fine white powder (50.5 grams; 91% yield) having amelting point range of 137°-141.5° C.

The carboxylic acid content (as determined by KOH/pyridine titration)was two equivalents/mole. Elemental analysis (calculated) for the whitepowder product was C:69.04%, H:7.96% and O:22.99%. Elemental analysis(found) was C:69.11%, H:7.98% and O:22.91%.

EXAMPLE 2

This example demonstrates the preparation of the compound represented byStructure II.

About 25 grams (0.089 mole) of the Structure I, Diels-Alder adductproduct prepared according to the procedure of Example 1, were dissolvedin a two phase mixture of chlorobenzene (50 grams) and water (50 grams,pH=7.4).

Sodium periodate (10 grams), potassium permanganate (0.45 gram) andtetrahexyl ammonium iodide (1.0 gram) were added and dissolved in theaqueous phase.

Next, a Lemieux-Von Rudloff oxidation was carried out at 25° C. for 22hours and the residual oxidizing agent was destroyed with the additionof 2.5 grams of sodium hydrogen sulfite.

The organic layer (off yellow color) was separated and dried over 3.0grams of magnesium sulfate. The drying agent was filtered and thechlorobenzene solvent was removed under vacuum (0.5 mm/40° C.).

The product which remained (Structure II; R=methyl) was a pale yellowoil (30.6 grams, 100% yield). The elemental analysis, the ¹ H NMR andthe ¹³ C NMR data obtained for the Structure II product are summarizedbelow in Table I.

                  TABLE I                                                         ______________________________________                                        Analysis and Data for the Compound of Structure II                            ______________________________________                                        Elemental Analysis:                                                                         carbon     hydrogen oxygen                                      Calculated (%)                                                                              56.14      6.47     37.37                                       Found (%)     56.58      6.52     36.91                                       .sup.1 H NMR (δ, CDCl.sub.3):                                            ##STR3##                                                                      ##STR4##                                                                     10.8, broad singlet, 2H (D.sub.2 O exchangeable)                              .sup.13 C NMR (decoupled, ppm, CDCl.sub.3):                                   27.5 ( .sub.--CCO.sub.2 H)                                                     ##STR5##                                                                      ##STR6##                                                                     179 ( .sub.--CO.sub.2 H)                                                       ##STR7##                                                                     ______________________________________                                    

EXAMPLE 3

This example demonstrates the preparation of two of the compounds ofthis invention represented by Structures III and IV.

About (30.6 grams (0.089 mole) of the oxidized Diels-Alder adductproduct (Structure II) prepared according to the procedure of Example 2,were dissolved in aqueous tetrahydrofuran (40% water) and neutralizedwith two equivalents of 50° C. triethylamine (18 grams, 0.178 mole).

The resulting solution was added to a 500 milliliter aqueous solution ofsodium cyanide (17.5 grams, 0.357 mole) and hydrazine sulfate (23.14grams, 0.178 mole).

The resulting solution was stirred for 3 hours at 45° C., then cooled toroom temperature. The reaction solution was then acidified (to litmus)with 1% aqueous hydrochloric acid solution.

A sample aliquot was taken and extracted with diethylether. The ethereallayer was dried over magnesium sulfate, filtered and the diethyletherwas removed under vacuum.

An off white powder product was isolated (m.p. 101° C.), analyzed andidentified as having the general formula of Structure III (R=methyl).Elemental analysis data of the product are summarized below.

    ______________________________________                                                 carbon                                                                              hydrogen   nitrogen oxygen                                     ______________________________________                                        Calculated (%)                                                                           54.28   5.92       25.32  14.46                                    Found (%)  54.97   6.00       25.12  14.79                                    ______________________________________                                    

The remaining acidified reaction solvent was cooled to 5° C. in an icebath and treated, dropwise, with a bromine/carbontetrachloride solution(18% Br₂, 10 g) over 20 minutes. Excess bromine was destroyed with 5grams of sodium hydrogen sulfite.

A white solid was isolated after extraction with diethyl ether, dryingwith magnesium sulfate and removal of the ethereal solvent.

The solid product was washed extensively (5×200 ml) with cold (5° C.)water, then dried in a vacuum desicator over calcium sulfate.

The white solid was recovered (28.6 grams, 73% yield) and was found tohave a melting point of 132° C. (decomposition). Structure assignment(Structure IV) was made based on ¹ H NMR, ¹³ C NMR and ¹⁵ N NMR data setforth in Table II.

                  TABLE II                                                        ______________________________________                                        Compound NMR Data of Structure IV                                             ______________________________________                                        .sup.1 H NMR (δ, CDCl.sub.3):                                           1.45, singlet, 12H                                                                                    ##STR8##                                              1.8, doublet, 4H, J = 4H.sub.z                                                                       Geminal                                                1.9, doublet, 4H, J = 4H.sub.z                                                                       CH.sub.2                                               11.2, singlet, 2H, D.sub.2 O exchangeable                                     .sub.13 C NMR (decoupled, ppm, CDCl.sub.3):                                   12.5                                                                                                  ##STR9##                                              27.5                   ( .sub.--CCO.sub.2 H)                                  28.5                   ( .sub.--CH.sub.2)                                     53.6                                                                                                  ##STR10##                                             122                    ( .sub.--CN)                                           181                    ( .sub.--CO.sub.2 H)                                   .sup.15 N NMR (ppm, CH.sub.3 NO.sub.2 relative):                              -122.21                (C .sub.--N)                                            136.58                ( .sub.--N .sub.--N)                                   ______________________________________                                    

EXAMPLE 4

This example demonstrates the preparation of the initiator of thisinvention represented by Structure V with each R representing a methylmoiety.

About 28.6 grams (0.065 mole) of the bicyclic azo compound of StructureIV, prepared using the procedure of Example 3 were dissolved in 200 mlof a mixture of tetrahydrofuran:water (2:1 vol/vol).

The resulting solution was cooled to 0° C. in a ice/sodiumchloride/water bath and triethylamine (13.1 grams, 0.180 mole) in 50milliliters of tetrahydrofuran was added to the solution.

The reaction mixture was cooled to -20° C. with a dry ice/acetone slurryand a solution of ethyl chloroformate (3.51 grams, 0.032 mole) in 50milliliters of tetrahydrofuran was added to the reaction mixture over 20minutes.

The reaction mixture was stirred at -20° C. for one hour and a solutionof sodium azide (2.2 grams, 0.032 mole) in 100 milliliters of water wasadded over a one hour period.

The reaction mixture was allowed to warm to -5° C. and stirred again forone hour.

The reaction mixture was diluted with 1.5 volumes of water resulting inthe precipitation of a pale yellow powder. The powder was purified bydissolving it in chloroform and precipitating with excess petroleumether.

The pale yellow powder (20.3 grams, 70% yield) was found to have amelting point of 77° C. (decomposition) and was analyzed by infrared, ¹H NMR, ¹³ C NMR and ¹⁵ N NMR spectroscopy. On the basis of the followingspectral data set forth in Table III, Structure V, [2, 5, 8,11]-tetramethyl-[2, 5, 8, 11]-tetracyano-cis-6a' carboxy, 12a'oxoazide-3,4:9,10 bisdiazobicyclooctane, was assigned to the product.

Infrared (CM⁻¹, CHCl₃): 1687 ##STR11##

¹ H NMR (δ, CDCl₃): 1.45, singlet 12H, 1.8, doublet×doublet, 4H J=4.5Hz, 1.88, doublet×doublet, J=4.5 Hz, 11.0, singlet, 1H, D₂ Oexchangeable.

¹³ C NMR (decoupled, ppm, CDCl₃): 12.5 ##STR12## 28.8 (--C--CO₂ H); 30.1(--C--CON₃); 28.1, 29.5 (--CH₂ --); 53.7 ##STR13## 122.2 (--C.tbd.N);##STR14##

¹⁵ N NMR (ppm, CH₃ NO₂ relative) ##STR15##

Structure V, the bisdiazobicyclooctane initiator of this inventionconsists of two azo linkages which can be thermally activated to formradical species which will initiate the free radical polymerization ofany suitable free radical polymerizable monomer. And the γ-carboxycarbonylazide moiety will undergo a condensation reaction with onehydroxyl, amine or mercapto terminated polymer. Accordingly, thecompound of Structure V is suitable for use as a polymerizationinitiator and as such is capable of producing radial block polymershaving up to five arms, four of which can be identical.

It will be evident from the foregoing that various modifications can bemade to this invention. Such, however, are considered as being withinthe scope of the invention.

What is claimed is:
 1. A compound having the formula ##STR16## whereineach R separately represents a methyl or ethyl moiety.
 2. A compoundhaving the formula ##STR17## wherein each R separately represents amethyl or ethyl moiety.